Color backed motion picture film



ug. 9, 1932. J. B. WELLS COLOR BACKED MOTION PICTURE FILM Filed May 17, 1930 Flll' Emulsion.

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Patented Aiug. 9, 1932 .1JN1TED STATES PATENT ori-*lcs JACKSON B. WELLS, OF ROCBZESTER,VNEW YORK, ASSIGNOR TO EASTMAN KODAK COM- PANY, OF ROCHESTER, NEW YORK, A CORPORATION OF YORK COLOR BACKED MOTION PIGIURE FILM Appucation inea my 17,

This invention relates to motion picture lm, and particularly to the type of film which is backed with a dye which later bleaches out during processing.

. In the case of amateur motion picture particularly, where excessively contrasting lightings are sometimes encountered, ,1t has been customary to some extent to back the lilm with a dye designed'to eliminate halation. The dyes used bleach out on processing the film and disappear. In the case of the ordinary cellulose acetate support it is sometimes diiiicult to completely bleach out certain of the desirable dyes. This is, of course, objectionableas a certain tint or over-all grayness remains over the image.

An object of this invention is to facilltate the bleaching out of colored backings put on for the purpose indicated. 0

The single figure ofthe accompanying drawing shows in perspective and cross-sec- `tion an embodiment of my invention.

I have found that a thin backing of cellulose acetate of a definite description coated on the regular cellulose acetate support, but

under the color backing, permits the nonhalation dye to bleach out more perfectly than an unbacked support.

The kind of cellulose acetate I employ for this intermediate backing is one of relatively low precipitation value, and one which gives a clear solution containing a minimum amount of haze or insoluble particles of acetate when dissolved in acetone. I have found that in making up these solutions these 'iine particles which are not soluble in acetone cannot be removed by filtration and therefore give trouble when cotton is used showing this haze. On the other hand, solutions 'which show no haze Vare desirable for the application of the undercoat as I use it.

The term precipitation value is Ian arbitrary one and is defined in co-pending application Serial No. 353,649, filed by A. F. Sulzer, April 8, 1929. The term precipitation value is applied tothe results of certain definite tests which are carried out inthe following way. vFive grams ofthe dry cellulose acetate are accurately weighed and placed l in a wide-mouthed 12 ounce bottle. To this .value which equals the per -cent acetate preisen. serial No. 453,341.

are added 100 cc. of acetone (commercial grade of 99% or better), and the mixture is stirred until homogeneous. The bottle should be closed during the stirring with a rubber stopper tted with a shaft for the stirrer. To this dope is added slowly from va pipette (and with thorough stirring 150 cc. of a mixture consisting of two parts of distilled water and one part of acetone by volume. Care should be taken to keep the solvent mixture at 20o centigrade wherever volumes are 'being measured.

At the end of the addition of the acetone and water mixture, a mixture is obtained containing 40% water by volume (neglecting contraction) in which is suspended the precipitated acetate. This is allowed to stand for 12 hours at. 20 centigrade. 25 cc. of the clearest portion (super-natant solution) are removed with a pipette. At the end of this time precipitation has reached equilibrium and proceeds no further, and during the same time settling of the precipitate occurs. This 25 cc. is centrifuged in stoppered bottles at high speed until the liquid is perfectly clear. Exactly 5 cc. of the clear liquid are removed with a pipette and evaporated t0 dryness on av weighed watch glass. If W is the weight of the residue in grams, the. precipitation.

cipitated,

= 10o Wxx x100Y The cellulose acetate which I use has pref- I erably a precipitation value of about. 70%

when calculated iny this manner. I may use.

kwith the film forming operation.A After the main body of the support 3 is formed, pref- `rably of a composition includingcellulose gives a clear solution with a minimum amount of haze 1n acetone, and a color backacetate of high precipitation value, that is g over 75% and preferably over 90%, I next apply to it a thin solution of approximately 21/27 of cellulose acetate of the type specified in acetone, for'`v example. ,Other suitsible solvents of course may be employed, but

acetone is usually preferable. The operation of a plying a thin coating of cellulose acetate 1s carried out on a coating machine of a N well known type. This coating 4.- dries very .and include broadly any dyes suitable for the purpose. It is also understood that any .dye used in this manner must be capable of bleaching out or washing out in the subsequent processing of the film, thatis', in the developer, the fixing bath, or the wash water.

The product as made by my invention may best be understoody by reference to the drawing. A regular cellulose acetate 4support 3 has4 coated on vit'the intermediate acking 4 of acetate .of low precipitation value. The outer face of the coating 4 car'-, ries the colorbacking-or dye layer` 5. The

opposite side of the support carries the emulsion layer 2. As used for motion pictures the films has the regular perforations 1.

I have found'that color backed film made in accordance with this invention bleaches out clearer than if the special' acetate under.- coating had n o't -been used. The advantages of having a clear print after processing are readily apparent since such aprint will give a cleaner picture on projection, will be better for sound reproduction, and will also require less light on exposure if other prints are made from it.

What I claim is:

1. A photographic film base comprising a support of cellulose acetate, an intermediate backing of cellulose acetate of low precipitation value -and a color backing.

2. A photographic. film base comprising a support of cellulose acetate, an intermediate backing of cellulose acetate of a precipitation yalue of the order of and a color backing. 3. A photographic film base comprising a support of cellulose acetate, an intermediate backing of cellulose acetate of a precipitation` value of the order of 70% and which 4. A photographic film base comprising successively a support of cellulose acetate, an intermediate backing of cellulose acetate of low precipitation value and a superficial coating of a dye thereon.

5. A photographic film base comprising a support of cellulose acetate and an intermediate backing of cellulose acetate of low precipitation value having thereon a superficial coating of a dye which prevents halation.

6. A photographic film base comprising a support of cellulose acetate and an intern mediate backing of cellulose acetate of low precipitation value having thereon a superficial coating of a dye which prevents halation and which bleaches out in the photographic processing baths.

7. A photographic film base comprising a support of cellulose acetate of high precipitation value and an intermediate backing lof "cellulose acetate of substantially lower precipitation valuehaving thereon a superficial coating of a dye which prevents halation and which bleaches out in the photographic processing baths. y

8. A photographic film base comprising a support of cellulose acetate and an intermediate backingof cellulose acetate of a precipitation value not over 75% having thereon a superficial coating of a dye which pre-Y y vents halation and which bleaches out in the photographic processing baths.

' Signed at Rochester, New York, this 12th day of May, 1930.

i JACKSON WELLS. 

